This application claims the priority of Korean Patent Application No. 2003-4243, filed on Jan. 22, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an air conditioner for a vehicle, and more particularly, to an air conditional for a vehicle, which has an improved air passage structure for higher early stage cooling efficiency, allows easy drainage of condensed water from an evaporator, and can be made slim according to various requirements of vehicle makers.
2. Description of the Related Art
In general, air conditioners for vehicles, which control the interior temperature and humidity to provide delightful driving conditions, include a cooler and a heater. The cooler generates cool air by evaporating a coolant coming into an evaporator using a latent heat of vaporization taken from air flowing around the evaporator and supplies the generated cool air into the interior compartment of the vehicle. The heater circulates cooling water heated by the heat taken from the engine along a heater core to heat air surrounding the heat core and supplies the heated hot air into the interior compartment of the vehicle.
To this end, a general air conditioner for a vehicle includes a case with an internal air passage along which external air that is blown through a blower unit flows, and cooling and heating heat exchangers disposed at both ends of the air passage to produce cool air or hot air.
Such air conditioners for vehicles are classified into semi-center mount type air conditioners and center mount type air conditioners depending on the location of the blower unit. Semi-center mount type air conditioners have a blower unit in a side portion of the case with an air passage connected to the blower unit to supply air through the air passage in the case. Center mount type air conditioners have a blower unit in the middle of the case with an air passage to directly supply air blown through the blower unit to the air passage.
FIG. 1 is a sectional view of a conventional air conditioner for a vehicle. Referring to FIG. 1, a conventional air conditioner includes a case 1 with an internal air passage 3 through which air that is blown through a blower unit 2 flows, an evaporator 4, which is a cooling heat exchanger arranged in the internal passage 3 of the case, and a heater core 6, which is a heating heat exchanger arranged next to the evaporator 4 in the internal passage 3. A tamp door 5 controls opening and closing of a connection passage between the evaporator 4 and the heater core 6 to guide air from the evaporator 4 toward the heater core 6. Air blow direction switching doors 9 are opened or closed depending on the mode chosen by a passenger to allow cool air or hot air to be discharged through openings 7 and 8.
However, the following problems arise with the conventional air conditioner for a vehicle structured as described above.
First, the evaporator 4 is arranged almost perpendicular to a bottom wall 1a of the case 1 so that a portion of the evaporator 4 is too far from the interior wall of the case 1, thereby requiring a longer inlet/outlet pipe 48, which is connected to the evaporator 4.
Second, water condensed by the evaporator 4 drops and is scattered by air flowing near the evaporator 4, so that it is difficult to expel the condensed water. The scattering water vaporizes near the heater core 6 and degrades the performance of the heater core 6.
Third, due to the arrangement of the evaporator 4 almost perpendicular to the bottom wall of the case 1, a larger space is required for the evaporator 4 in the case 1, thereby making it difficult to manufacture slimmer air conditioners.
Fourth, since air to be cooled is allowed to pass the evaporator 4 only one time, it is difficult to expect satisfactorily high cooling efficiency at an early stage of operating the vehicle or in the summer season.
Fifth, the structure of the evaporator is unsuitable for slimmer, higher efficiency air conditioners.
In an air conditioner for a vehicle, which is disclosed in JP Laid-open Patent Publication No. 2001-158216, hot air is preliminarily dehumidified in an auxiliary cooling zone of a cooling heat exchanger before entering a main cooling zone, thereby suppressing condensation of air into water in the main cooling zone. In addition, the auxiliary cooling zone is located under the main cooling zone at an angle, so that condensed water generated in the main cooling zone is allowed to drop into the auxiliary cooling zone to be discharged more efficiently together with condensed water which is generated during dehumidification in the auxiliary cooling zone. Furthermore, the cooling heat exchanger ranges over a wide area, through both ascending and descending passages, so that a smaller, more efficient air conditioner can be implemented with this cooling heat exchanger.
However, in the air conditioner, the air that is blown through the blower unit flows through the auxiliary cooling zone and then the main cooling zone of the evaporator. As a result, the air volume is reduced while passing the auxiliary cooling zone, and more noise is generated.